Add Decompress helper functions to "String" type

[kunalmohan]

String type could have gzip helper functions such as "IsGzip" and "GzipDecompress()" functions for use as below:

he.GET("/data/abc.bin").
                WithHeader("Range", "bytes=0-2000").
		Expect().
		Status(http.StatusOK).
		HasContentType("application/octet-stream").
		Body().
		GzipDecompress().
                IsEqual(expectedData[:2000])

Or alternatively a generic decompress method that takes compression type as parameter:

he.GET("/data/abc.bin").
                WithHeader("Range", "bytes=0-2000").
		Expect().
		Status(http.StatusOK).
		HasContentType("application/octet-stream").
		Body().
		Decompress("gzip").
                IsEqual(expectedData[:2000])

[gavv]

I think this would be a legit feature. I'd prefer a generic function, and a enum parameter instead of string. Also, Decompressed would be a better name because other methods that return nested values don't use verbs. So it would look like:

he.GET("/data/abc.bin").
		WithHeader("Range", "bytes=0-2000").
		Expect().
		Status(http.StatusOK).
		HasContentType("application/octet-stream").
		Body().
		Decompressed(httpexpect.EncodingGzip).
		IsEqual(expectedData[:2000])

I don't have much time now, so I'll add help-wanted tag. Patches are welcome.

[milanrajani]

Hi, I would like to work on this issue. Could you please assign it to me if it's still available?